Revista de la Construcción. Journal of Construction

Enhancing the mechanical properties of fibre reinforced concrete using diatomaceous earth powder: fresh and hardened properties of concrete

2024-06-17T16:09:58+00:00

This research investigated enhancing the mechanical properties of fibre-reinforced concrete using diatomaceous earth powder. A total of six mix groups were designed as M40 grade concrete according to IS: 10262 – 2019. Each mix group consisted of six mixes. The study examined the fresh and hardened properties of the fibre-reinforced concrete, including workability, Compressive Strength (CS), Split Tensile Strength (STS), Flexural Strength (FS), and Modulus of Elasticity (ME) at various ages. The first three groups incorporated Electronic waste (E-waste) fibres, added to the concrete by weight of cement (0.2%, 0.4%, 0.6%, 0.8%, and 1%) with lengths of 30mm, 40mm, and 40mm, respectively. Additionally, diatomaceous earth powder partially replaced cement in amounts of 5%, 10%, 15%, 20%, and 25%. Based on experimental observations, the optimum fibre content was 0.8% for group 1 and 0.6% for groups 1 & III. Similarly, the same optimum fibre content was used for groups IV-VI. Including E-waste fibres and diatomaceous earth powder enhanced the mechanical properties of the concrete. The experimental study revealed that groups I and VI performed better than the remaining mixed groups. Specifically, for group I, the CS, STS, and FS improved by 9.86%, 4.85%, and 4.96%, respectively, while for group VI, these properties improved by 8.82%, 5.60%, and 4.57%. The physical properties of concrete strength were also compared using linear regression analysis and various codes. The regression equations aligned well with the experimental test results and aided in predicting those results.

Nonlinear finite element study on the improvement of torsional strengthening of RC beams with diagonal shear reinforcement

2023-12-19T16:00:26+00:00

Experimental and numerical studies are carried out by many researchers in order to examine the nonlinear behavior of reinforced concrete (RC) beams under the torsion moment and to improve the torsional moment capacity. In this study, a numerical study is performed to investigate efficiency of diagonal shear reinforcement (DSR) on the response of RC beams subjected to pure torsion. A nonlinear numerical model was constituted to simulate the response of the RC beams by using ABAQUS software program and verified with the selected experimental results from literature. The numerical analysis results proved that the nonlinear numerical model is quite successful in simulating the nonlinear behavior of RC beams and DSR makes a very significant contribution to the torsional moment capacity of the RC beam subjected to pure torsion.

Potential implementation of the woody biochar waste as an eco-friendly soil stabilization material in sandy environments

2024-07-08T13:50:39+00:00

This experimental analysis aims to develop a fundamental understanding of the geotechnical properties of soils treated with an organic material named biochar. In this context, an experimental protocol was set using the Casagrande shear box apparatus to effectively demonstrate the combined influence of the biochar fraction (F_bio=0%, 5%, 10% and 15%), the initial relative density (D_r = 20%, D_r= 54%, and D_r= 90%), and the initial normal stress (σ_n = 100, 200, and 300 kPa) on the mechanical behavior of Chlef sand. The obtained results clearly show that biochar has a significant influence on the mechanical behavior of the tested materials. Additionally, the shear strength decreases with increasing biochar content up to a threshold value of (F_bio = 10%). Beyond that, the shear strength increases with the increase of biochar content up to the value of (F_bio= 15%) for all the considered parameters. The observed trend of increasing shear strength with the addition of the biochar content (F_bio = 15%) can be attributed to the amplification of the particle interlocking due to the presence of biochar particles between the large particles of Chlef sand, inducing an increase in the dilative character of the tested materials; offering implications for various geotechnical applications. Moreover, pertinent correlations were obtained between the residual shear strength and the grain size characteristics of the sand-biochar mixtures.

Effect of discarded smooth and rough glass waste on mechanical properties of cement concrete

2023-12-17T21:05:28+00:00

The depletion of natural material leads to an alternative material in its place in concrete. If the alternative material is a recycled material, it serves the purpose of reuse and reduces its impact on the environment. One such material is glass waste. In this study, two varied textures of transparent waste glass of size 12.5 mm are used as an alternative material for coarse aggregate with 10, 20, and 30% of replacement. The mechanical properties such as compressive strength, flexural strength and split tensile strength are studied along with water absorption and unit weight characteristics. It is observed that the compressive strength showed a maximum value at 10% replacement for both textured glasses, beyond that it reduces irrespective of curing period. A similar trend is observed in flexural strength also. The split tensile strength increases with percentage replacement due to the contribution of waste glass in interface transmission zone. The water absorption falls well within 3% for all the combinations indicating its good behaviour. The unit weight decreases making it suitable for making lighter material. When comparing cost, there is a reduction in cost by 3 to 7 %; however, it is minimum it addresses the environmental aspects.

Numerical estimation of the subgrade reaction modulus of a horizontally loaded piled raft

2023-10-29T22:02:51+00:00

A horizontal full-scale test was executed in a piled raft with a single pile. Later, from those measured experimental results, some numerical simulations were carried out using a commercial software Abaqus 2019 obtaining acceptable approximations. During the numerical analysis, the elastic-plastic behavior of each material comprising the foundation system has been considered, including the soil, the concrete, and the steel. Based on such numerical approximations, a polynomial function that represent the pile deflections along the pile shaft has been calculated and plotted. Later, from this function the rotation, the bending moments, the shearing forces, and the load intensity along the pile were estimated; also, the subgrade reaction modulus of the soil was computed, and some p-y curves at specific depth points are presented according to the numerical results. Finally, this paper allowed obtaining a clear idea about the behavior and distribution of the internal forces not only in the foundation soil but also in the pile, from a success numerical performance.

Simulation of the behavior of reinforced concrete rectangular hollow sandwich plates under the effect of contact explosion through SPH method

2024-02-09T01:57:23+00:00

When dealing with contact explosion, a type of explosion load that has a substantial impact on structures, it is necessary to use a distinct approach compared to other types of explosion loads. Hence, utmost significance should be attributed to the selection of the analytical approach when modeling the explosion. It is crucial to ascertain the behavior of the explosion pressure in the space between hollow sandwich plates. This work involved conducting experiments to examine the accurate simulation of hollow plates subjected to contact explosions, which result in a reduction in the dispersion of explosive pressure. The structure was modeled using smooth particle hydrodynamics (SPH) and Lagrangian modeling techniques, taking into account the effects of explosives and contact explosions. The mesh-free structure of these approaches makes them highly successful in resolving significant deformations resulting from explosions. The comparison criteria included the widths of the crater pits on the upper surface of the plate, the behavior of the explosion pressure in the structure cavity, and the impact of the explosion load on the lower section of the plate. After evaluating several explosion load and hollow structure modeling methodologies, it was concluded that the most appropriate approach for reproducing the experimental results involved using Smoothed Particle Hydrodynamics (SPH) to model the explosive and Lagrangian method to model the structure.

Prediction of capillary absorption and compressive strength, applying multiple linear regression and artificial neural networks in concrete with natural pozzolana addition

2024-05-21T20:51:48+00:00

Cement is the fundamental binder of concrete, and its manufacture has a significant impact on the environment; therefore, it is necessary to look for eco-sustainable alternatives, including additions such as natural pozzolana, which affect the internal matrix of concrete and therefore the compressive strength and capillary absorption of concrete. In this context, prediction models for capillary absorption and compressive strength of concrete with pozzolana additions have been determined by applying linear multiple regression tools and artificial neural networks which will help reduce laboratory testing costs and times. For this purpose, 16 types of mixtures were designed with w/c ratios of 0.40, 0.45, 0.50 and 0. 55 and addition of 10, 15 and 20% of pozzolana; 160 cylindrical samples were manufactured and tested in laboratory, the values of capillary absorption and compressive strength at 28 and 56 days of curing were determined; the effect of each variable on the results obtained indicated that 15% pozzolana significantly improved the properties studied; using the data of the manufacturing variables of each design and the results of capillary absorption and compressive strength, prediction models were obtained for both properties; the best back propagation neural networks (BPNN) structure is [10,20,10,1], with R²_compression=0. 9486 and R²_{capillary absorption}=0.9756; while the models obtained with multiple linear regression obtained R²_compression = 0.9391 and R²_{capillary absorption} = 0.8693; both techniques showed a high reliability for the prediction of compressive strength and capillary absorption.

Comparative study on the linear and nonlinear dynamic analysis of typical RC buildings

2024-07-29T20:15:05+00:00

A careful evaluation has been carried out to reveal advantages and disadvantages of linear and nonlinear modelling in dynamic analysis. 4- and 7- story building models representing characteristics of about 500 existing buildings models in Turkey was used in analyses. In the study, displacement demand parameters such as roof drift ratio and interstory drift ratio obtained from linear and nonlinear analyses were compared using a total of 24 ground motion records including forward directivity effects (Set 2) as well as records (Set 1) recorded in type B and C soils. Although the seismic demands for Set 2 are obtained extremely high in the nonlinear models, the demand differences between Set 1 and Set 2 are not excessive for the linear models. In the region where the T/T_p ratio is close to one, the linear analysis predicts unrealistically high demands compared to the nonlinear analysis. Linear analysis results mostly show an increase or decrease depending on dynamic amplification effects. The effects of ground motion intensity and damage mechanism cannot be observed in linear analysis method. For all these reasons, it is recommended not to prefer linear modeling method when using time-history analysis.

Effective net area of failure in steel plates subjected to tension

2024-06-28T20:00:52+00:00

The current design of plates in tension due to the limit state in tensile rupture according to the requirements outlined in ANSI/AISC 360 (2016) establishes that the effective net area value (Ae), must be the net area value (An), but did not be greater than 0.85 of the gross area (Ag) of the element. The research aim was to evaluate the experimental behavior of the effective net area of failure concerning 0.85Ag of steel plates subjected to tension load conduct to reliable or unsafe design. Thirty-five specimens of A36 steel with different arrangement of holes were tensile tested. Five different plates thicknesses were considered from 3.1 mm (1/8”) up to 9.5 mm (3/8”). The behavior of the effective net area of failure is discussed in term of the slenderness ratio of steel plate, the effective net area of design and analyzed based on current design specifications. The results showed that the effective net area of failure of the undrilled specimens presented a slight tendency to increase with increasing slenderness ratio. In the specimens with two rows of holes and staggered holes this tendency decreased. Whereas for the specimens with one rows of holes the effective net area of failure did not present a clear behavior with respect to slenderness ratio. Moreover, the undrilled specimens of this study developed an effective net area of failure greater than the effective net area of design, satisfying the design specifications. But in the specimens with holes the effective net area of design was greater, generating unreliable designs. In other words, the 0.85Ag value was found adequate for the specimens without holes. Nevertheless, this value was high for the specimens with holes in this experimental research.

Key factors in the acquisition of residential properties: A comprehensive study of the global real estate market

2023-12-23T19:40:22+00:00

Housing is a fundamental need in contemporary society, and its acquisition by families worldwide is on the rise. Acquiring a residence involves a multifaceted and intricate procedure that encompasses numerous crucial elements. This study examines the factors affecting purchase expectations in the global residential real estate market through an exhaustive bibliometric search using a systematic review. The results are synthesized, and significant dimensions of the studied variable are identified. Among the key considerations in property acquisition are price, design, location, and developer reputation, as these factors can impact functionality, quality of life, and the emotional and psychological well-being of residents. This study provides valuable insights into the trends and dynamics of the global residential real estate market, benefiting both academics and industry professionals.

Rheological behaviour of cement mortar with recycled organic sand

2024-02-27T19:57:25+00:00

The aim of this paper is the study of rheological behaviour of the recycled organic sand (ROS) in cement mortar, using derived sand from recycled asphalt pavement (RAP). Four substitutions amount of ROS sands (25%, 50%, 75%, and 100%) against the weight of natural sand (NS) were used to obtain M 25, M 50, M 75, and M 100 respectively which were compared with the reference mortar M 0. In this study, the water/cement (w/c) ratio was kept constant at 0.55 for all mixtures. Fresh properties were given form slump test and spread measurements, when, the rheological parameters such as shear stress, yield stress and plastic viscosity were obtained by using a rotating Anton Paar rheometer; the test result shows that both of slump and spread were negatively affected by increasing the sand substitution. The shear stress, yield stress and plastic viscosity were increased with the increasing the substitution amount. All mortars followed the Bingham model until 50% of ROS substitution, after this amount, the obtained mortars were segregated.

Investigation of wear performance of GFRP profiles under different environmental conditions

2024-07-29T16:35:39+00:00

Continuous exposure to external factors leads to loss of physical and mechanical properties in building materials due to wear effects. There is little information available on the wear performance of glass fiber reinforced polymer (GFRP) composite profiles, whose usage areas are increasing, under various conditions. In this study, the aim is to determine the wear performance of GFRP box profiles under different conditions. To evaluate the wear performance of GFRP profiles under various conditions, their performance was compared with the wear performance of concrete under different strengths and conditions. The effects of fiber direction, temperature, and cold conditions on the wear performance of GFRP box profiles were investigated. The effects of compressive strength, age of concrete, humidity status, temperature, and cold conditions on the wear performance of concrete were experimentally determined and compared. The wear results of GFRP profiles tested in the Böhme wear test machine and the wear results of concrete in three strength classes were evaluated and compared under different conditions. In addition, the test numbers were increased using the Monte Carlo Simulation method to evaluate the possible result range. The wear losses of GFRP profiles increase with increasing temperature while they perform well under cold conditions. It was observed that GFRP box profiles in the horizontal fiber direction exhibited greater mass and volume loss. Concrete showed a decrease in mass loss as compressive strength increased. Similarly, the wear loss in concrete decreased as the age of the concrete increased, with the greatest mass and volume loss occurring in 3-day-old concrete.